Can I file small claims suit against roommate?

Ok, so my roommate and I have gotten into several verbal altercations and I am just trying to get a little advice. We are both on the lease and have been splitting all bills equally (rent, electric, cable, water/swr). Recently she has been running the electric bill through the roof because she has been wastefully using the air and refuses to change her habits. I have tried to speak with her about it, but she refuses to change...I have accepted this and am willing to just split whatever ridiculous amount the bill is because my lease with her ends Aug 30th....My question really involves the electric bill. The bill is in my name and we do not have a signed contract HOWEVER I have the original ad I posted on craigslist that she answered saying that all utilities and rent would be split evenly. I also have an email to her that was sent when she answered my ad saying the exact same thing. Weve lived together for two years and she has always paid the bill online using her debit/check card. Previously I always paid her in cash for all bills (which have always been paid on time) but due to the issues weve been having ive opted to pay by check for the last month (June) and this month (July) which I have proof of. I also have a document in which she writes what each of us is responsible for paying each month.... My question is, if she doesnt pay this month or for the last month can I file a claim against her??? Please let me know.